Open Radar

 
Summary: NSInvocation does not work with methods that return structures that contain unions or bitfield types. Instead exceptions are thrown (and an NSException is overreleased). 

Steps to Reproduce:
Create a new Mac OS X target. In main.m, paste: 

static void test_failure(const char *file, int line)
{
    NSLog("Test failure at %s:%d\n", file, line);
}

BOOL _testassert(BOOL b, const char *file, int line)
{
    if (!(b))
    {
        test_failure(file, line);
        return NO;
    }

    return YES;
}
#define testassert(b) do { if (!_testassert(b, __FILE__, __LINE__)) return NO; } while (NO)


@interface TestHelper : NSObject
@end
@implmentation TestHelper
union floatInt {
    int a;
    float b;
};
struct hugeStruct {
    double a;
    char b;
    int c;
    short d;
    long long e;
    char *f;
    SEL g;
    id h;
    NSRange i;
    NSObject *j;
    int *k;
    void (^l)(void);
    int *(*m)(int *);
    struct charDoubleStruct n;
    union floatInt o;
    IMP q;
    Class r;
    int s[5];
    char t:1;
    char u:3;
    char v:4;
    volatile int x;
    float y;
    
    
};

int *foo(int *bar) { return bar; };
int *baz(int *qux) { return NULL;};

- (struct hugeStruct)hugeStructRetMethod
{
    int *k = NULL;
    struct hugeStruct ret = {
        M_PI,
        'b',
        1234567,
        -1234,
        1234567891011,
        (char *)NULL,
        _cmd,
        @protocol(NSCoding),
        NSMakeRange(123, 321),
        @"Foo",
        k,
        [^{} copy],
        foo,
        { 'a', M_E },
        9001,
        [self methodForSelector:_cmd],
        [self class],
        { 4321, 1234, 5678, 8765, 9101112},
        1,
        3,
        6,
        70,
        4.42f
    };
    return ret;
}

- (BOOL)testHugeStruct
{
    NSInvocation *inv = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:@selector(hugeStructRetMethod)]];
    [inv setSelector:@selector(hugeStructRetMethod)];
    [inv setTarget:self];
    int k = 51;
    char f = 'x';
    struct hugeStruct result = {
        M_PI_2,
        'f',
        7654321,
        4321,
        1110987654321,
        &f,
        _cmd,
        @protocol(NSCopying),
        NSMakeRange(500, 50),
        @"Bar",
        &k,
        nil,
        baz,
        { 'b', M_LN2 },
        90.5f,
        [self methodForSelector:_cmd],
        [NSInvocation class],
        { 42, 0, -1, INT_MIN, INT_MAX},
        0,
        0,
        0,
        77,
        41147.7
    };
    [inv invoke];
    [inv getReturnValue:&result];
    testassert(result.a == M_PI);
    testassert(result.b == 'b');
    testassert(result.c == 1234567);
    testassert(result.d == -1234);
    testassert(result.e == 1234567891011);
    testassert(result.f == NULL);
    testassert(result.g == @selector(hugeStructRetMethod));
    testassert(result.h == @protocol(NSCoding));
    testassert(result.i.length == 321);
    testassert(result.i.location == 123);
    testassert([(id)result.j isEqualToString:@"Foo"]);
    testassert(result.k == NULL);
    testassert(result.l != nil);
    testassert(result.m == foo);
    testassert(result.n.a == 'a');
    testassert(result.n.b == M_E);
    testassert(result.o.a == 9001);
    testassert(result.q == [self methodForSelector:@selector(hugeStructRetMethod)]);
    testassert(result.r == [self class]);
    testassert(result.s[0] == 4321);
    testassert(result.s[1] == 1234);
    testassert(result.s[2] == 5678);
    testassert(result.s[3] == 8765);
    testassert(result.s[4] == 9101112);
    testassert(result.t == 1);
    testassert(result.u == 3);
    testassert(result.v == 6);
    testassert(result.x == 70);
    testassert(result.y == 4.42f);
    
    return YES;
}
@end

and in main(), inside the @autoreleasepool scope:

TestHelper *h = [[TestHelper alloc] init];
[h testHugeStruct];

Expected Results: All tests pass

Actual Results: 
Several exceptions are thrown (and caught internally) by NSInvocation in the first line of -testHugeStruct. The first test fails and the method returns. When the autorelease pool drains, the app crashes as an already-released NSException is released.

Regression:
Unknown.

Notes:
Even if bitfields are not supported, there REALLY shouldn't be an overreleased NSException here. Also occurs in iOS 6.1 SDK.